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Old 03 December 2005, 05:36   #171
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Country: UK - England
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Boat name: Merlin
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Fair bit of catching up to do here for some of us


missus
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Old 03 December 2005, 05:53   #172
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Quote:
Originally Posted by The Jackeens
Fair bit of catching up to do here for some of us


missus
I think you'll find that you can catch the jet boat kwite kwickly with your 200 hp outboard.
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Old 04 December 2005, 12:32   #173
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Well, today went out on Steve and Carolines (Pressman) Jet Rib and what an awsome beast it is but handles lovely. the slow speed manouverability and control is superb, it can spin on a sixpense, you can cruise at 40 knots and then stop almost instantly. At high speed it can do some incredible tight turns. On the mooring it can move sideways and at slow speed it will go any direction you want it to.

I can see why folks have Jet Drives now, fantastic bits of Kit

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Old 04 December 2005, 13:28   #174
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And a photo of the Power units.
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Old 07 December 2005, 03:22   #175
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Country: UK - England
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Boat name: Merlin
Make: Solent 6.5
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Engine: 200
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Most recent helpful ideas (thanks) include :
  • water acting as 'bullets in machine gun fire'
  • the importance of the nozzle in the whole performance (without it an impellor acting as a prop in a tube i.e. bow-thruster) It also can change boat's direction :nozzle co-efficient ?
  • more of a focus on pressure rather than mass (although both play their part: the former more so in speed)
  • accelerating the water gives the action & subsequently there is a reaction (moving forward)
  • anyone got that video clip of the crazy jet-sprint boat spin mentioned where the acceleration is seemingly space age?
  • stator 'straightens out' water (flow?)
  • potential energy stored : kinetic energy released?
  • impellor applies force on water (mass)
  • there are one, two & three-stage jets
  • Bucket 'brakes'
  • Potatoes !!! Now you're talking my language
Please correct any misconceptions above.

Now stuck on the terms axial and centrifugal (and any other varieties!)

Please explain.

missus
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Old 07 December 2005, 04:17   #176
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Quote:
Originally Posted by The Jackeens
Now stuck on the terms axial and centrifugal (and any other varieties!)

Please explain.

missus
You want to keep that spoon don't you? (It has to be a new thread to qualify)

Axial - the shaft of the fan/pump is in line with the flow. (Co-Axial) The action is to push/pull along the pipe. Think bow thruster or modern hair drier.

Centrifugal - the shaft is at right angles to the exhaust flow. The stuff you are pumping goes in at the centre of the pump and is spun off the end of the vanes and usually exits ar 90º to the inlet. Think old style hair drier or submersible bilge pump.

Do you want to know about Vane, Roots, Screw and Piston (positive displacement) pumps?
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Old 07 December 2005, 15:35   #177
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Quote:
Originally Posted by Mark Halliday
You want to keep that spoon don't you? (It has to be a new thread to qualify)
Very thoughtful & I was chuffed

Quote:
Axial - the shaft of the fan/pump is in line with the flow. (Co-Axial) The action is to push/pull along the pipe. Think bow thruster or modern hair drier.

Centrifugal - the shaft is at right angles to the exhaust flow. The stuff you are pumping goes in at the centre of the pump and is spun off the end of the vanes and usually exits ar 90º to the inlet. Think old style hair drier or submersible bilge pump.
Need to digest that a bit more

Quote:
Do you want to know about Vane, Roots, Screw and Piston (positive displacement) pumps?
In for a penny, in for a pound. (Thing is I actually thought vanes were those yokes on top of chimneys with farmyard animals on them).

If they're central to jetboat function then please elaborate Sir Mark et al.
Thanks then!

missus
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Old 07 December 2005, 16:55   #178
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Quote:
Originally Posted by Mark Halliday
Do you want to know about Vane, Roots, Screw and Piston (positive displacement) pumps?
DE missis knoze orl abowt de rootz! er pAwl woz telin mee e ad tooo giv er fiftee kwid tooo gett herr rootz touchd upp. eye fink dat's wot shee ad touchd upp enywey
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Old 07 December 2005, 16:58   #179
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How does one report a bad post again. Must consult with the forum whingers



missus

(And you can behave and all Pierre Sept )
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Old 07 December 2005, 17:07   #180
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This is the business end of Pressman's 2 jets



and

This is what happens when you get too close to these jets.
me feckin camera took a bashing not to mention me





paul
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